The present invention relates to an overload protection device for a machine such as a motor, for turning the motor off in case of a mechanical overload on the machine shaft. More particularly, the invention relates to an overload protection device which includes driven disc means with overload springs holding the disc means in relation to a gear providing the external connection to the potentially overload producing load. The springs being situated inside of the annular disc means, and the device further includes a coaxial switching ring which upon turning of the ring discs actuates a switch for turning the motor off.
An overload protection device of the type to which the invention pertains is for example, shown in German Pat. No. 2,714,452. The device shown in this patent however is effective only in a uni-directional manner, particularly responding to the lifting of a lifting device. The rotational part can rotate in one direction only and is blocked against opposite direction overload. Thus, protection in this forbidden direction is not necessary. On the other hand, there are many areas in which a mechanical overload protection is desired to be effective in both directions of rotation.